Prudence

Prudence is the exercise of sound judgment in practical affairs. It is classically considered to be a virtue, and in particular one of the four Cardinal virtues (which are with the three theological virtues part of the seven virtues). The word comes from Old French prudence (13th century), from Latin prudentia (foresight, sagacity), a contraction of providentia, foresight. It is often associated with wisdom, insight, and knowledge. In this case, the virtue is the ability to judge between virtuous and vicious actions, not only in a general sense, but with regard to appropriate actions at a given time and place.

You're mistaken: men of sense often learn from their enemies. Prudence is the best safeguard. This principle cannot be learned from a friend, but an enemy extorts it immediately. It is from their foes, not their friends, that cities learn the lesson of building high walls and ships of war. And this lesson saves their children, their homes, and their properties.

You will hear every day the maxims of a low prudence. You will hear, that the first duty is to get land and money, place and name. "What is this Truth you seek? What is this Beauty?" men will ask, with derision. If, nevertheless, God have called any of you to explore truth and beauty, be bold, be firm, be true. When you shall say, "As others do, so will I. I renounce, I am sorry for it, my early visions; I must eat the good of the land, and let learning and romantic expectations go, until a more convenient season." — then dies the man in you; then once more perish the buds of art, and poetry, and science, as they have died already in a thousand thousand men. The hour of that choice is the crisis of your history; and see that you hold yourself fast by the intellect.

Ralph Waldo Emerson in "Literary Ethics" an address to the Literary Societes of Dartmouth College (24 July 1838).

A prudent and discreet Silence will be sometimes more to thy Advantage, than the most witty expression, or even the best contrived Sincerity. A Man often repents that he has spoken, but seldom that he has held his Tongue.

Since men almost always walk in the paths beaten by others and carry on their affairs by imitating—even though it is not possible to keep wholly in the paths of others or to attain the ability of those you imitate—a prudent man will always choose to take paths beaten by great men and to imitate those who have been especially admirable, in order that if his ability does not reach theirs, at least it may offer some suggestion of it; and he will act like prudent archers, who, seeing that the mark they plan to hit is too far away and knowing what space can be covered by the power of their bows, take an aim much higher than their mark, not in order to reach with their arrows so great a height, but to be able, with the aid of so high an aim, to attain their purpose.

Pliny the Elder, Natural History, XXIII. 8. 77. Giving the story of Pompey, who when he took the palace of Mithridates, found hidden the antidote against poison, "to be taken fasting, addite salis grano".